The wcstombs function converts a sequence of codes that correspond to multi-byte characters from the array pointed to by pwcs into a sequence of multi-byte characters that begins in the initial shift state and stores these multi-byte characters into the array pointed to by s, stopping if a multi-byte character would exceed the limit of n total bytes or if a null character is stored. Each code is converted as if by a call to the wctomb function, except the shift state of the wctomb function is not affected.
No more n bytes will be modified in the array pointed to by s. If copying takes place between objects that overlap, the behavior is undefined.